HUMAN ENTOZOA. 



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CHAPTER I. 



TBEMATODA. 



Importance of experimental research in hnman helmintliology — Species of entozoa 

 infesting man — The common liver fluke, or Fasciola hepatica — Greneral and specific 

 characters — History and nomenclature — Distribution and descriptive anatomy — ■ 

 Comparison with Fasciola ffiffantea—Q^ecial structural peculiarities. 



At the Cambridge Meeting of the British Association for the Ad- 

 vancement of Science, in 1862, I adduced the following argument 

 in favour of a more extended prosecution of experimental research 

 in the department of human helminthology : — " As man is infested 

 by a great variety of internal parasites, and some of them prove 

 exceedingly troublesome, it is evident that a large amount of prac- 

 tical good would ensue if we were more perfectly informed respect- 

 ing the origin and economy of these creatures ; for not only are our 

 personal interests directly affected by their intrusion, but we also suf- 

 fer indirectly from the injury and destruction they occasion amongst 

 our domesticated animals. At least tliirty well-marked forms 

 have been described as infesting the human body ; and although 

 most of the species are comparatively rare, yet a considerable num- 

 ber are exceedingly common in occurrence, and likewise often prove 

 numerically abundant in one and the same individual." 



This argument was supported by a reference to certain facts 



u 



